My cat hates my new dog help?

I NEED help here I brought home a 5 year old chihuahua terrier to foster in hopes of adopting. I have a cat who’s around 5 that I’ve had for 2 years who I truly didn’t think would mind the dog, she’s always been the friendliest cat I’ve ever known. Well I was WRONG my cat is not fond of the dog at all. She hisses... show more I NEED help here I brought home a 5 year old chihuahua terrier to foster in hopes of adopting. I have a cat who’s around 5 that I’ve had for 2 years who I truly didn’t think would mind the dog, she’s always been the friendliest cat I’ve ever known. Well I was WRONG my cat is not fond of the dog at all. She hisses at her and I’ve never heard my cat hiss up until now. I’ve mainly been keeping them separated with my cat in my room with everything she needs plus treats but I feel awful because I can’t give my cat much attention due to the dog crying and barking when I leave her alone. Ive tried having them both out a few times while I hold the dog and every time my cat slowly lurks toward the dog and starts hissing or she’ll just stare. I’m not sure whether my cat would actually hurt the dog, she hasn’t tried but who knows. I never saw this side of her until now. I want them both to be able to roam and have freedom but I have to be on edge watching their every move when I do. And keeping my cat in my room makes me feel beyond guilty. Should I let them around each other (with dog on a leash of course) more or should I just take the dog back? It’s only been 3 days, I know it may be a slow process for them to warm up but I just don’t know if I can handle separating them so much and my hearts breaking for my cat. But then if I return the dog I’ll feel horrible about that too! I want them both to be happy. Help! :(
10 answers 10